This invention relates generally to the structure of footwear. More specifically, this invention relates to the structure of athletic shoe soles that copy features of the underlying support, stability and cushioning structures of the human foot. For example, this invention relates to support and cushioning which is provided by shoe sole compartments filled with a pressure-transmitting medium like liquid, gas, or gel. The pressure-transmitting medium provides cushioning progressively, thereby causing tension in flexible and relatively inelastic sides of a shoe sole. These compartments of the shoe sole provide support and cushioning similar in structure to the fat pads of the natural human foot, which simultaneously provide both firm support and progressive cushioning.
Existing cushioning systems cannot provide both firm support and progressive cushioning without also obstructing the natural pronation and supination motion of the foot. This is because the overall concept on which existing shoe cushioning systems are based is inherently flawed. For example, existing shoe cushioning systems do not provide adequate control of foot motion or stability. Conventional systems are generally augmented with rigid structures on the sides of the shoe uppers and the shoe soles, like heel counters and motion control devices, in order to provide control and stability. Unfortunately, these rigid structures seriously obstruct natural pronation and supination motion and actually increase lateral instability.
In marked contrast to the rigid-sided designs, the human foot provide stability at it sides by putting those sides, which are flexible and relatively inelastic, under extreme tension. The tension is caused by the pressure of compressed fat pads, wherein the fat pads become temporarily rigid when outside forces make that rigidity appropriate, thereby producing none of the destabilizing lever arm torque problems of the permanently rigid sides of existing shoe sole designs.
Among other objects, this invention attempts, as closely as possible, to replicate features of the naturally effective structures of the human foot that provide stability, support, and cushioning.
This and other objects of the invention will become apparent from a detailed description of the invention which follows taken with the accompanying drawings.